Carbon Nanotubes: A Review on Structure and Their Interaction with Proteins
Table 5
Noncovalent immobilization by direct physical adsorption.
Protein or enzyme immobilized
Types of interaction
References
Lysozyme-CNT complex
(i) Hydrophobic regions on exterior of protein interact with the wall of CNTs through hydrophobic interactions. (ii) The π -π stacking interaction between the sidewalls of CNTs and the aromatic rings (both these hydrophobic and π -π interactions have been widely used to explain the driving force of the direct adsorption of many enzyme on CNTs). (iii) Electrostatic interaction. In addition to hydrophobic and π -π interactions, lysozyme interacts with the nanotubes through protonated amino moieties with defect sites of the CNTs at pH values lower than the isoelectric point. At pH levels higher than the isoelectric point, they interact via amine adsorption.
